A figure warp thread is pattern-determining through its appearance. This can be, for example, due to the colour of the figure warp thread or due to the material from which it is made, or due to the gloss or hairiness or thickness of the figure warp thread, or due to a combination of two or more of these appearance-determining characteristics. Two or more figure warp threads can also run parallel to one another in a fabric, so that the combination of their appearance-determining characteristics is pattern-determining.
‘Zone’ is used in this patent application in a very general sense to refer to a particular fabric surface, so that this term can mean not only a part of the surface of a fabric, but also the whole surface of a fabric. An at least partially pile-free fabric thus has at least one pile-free zone.
Each warp thread system comprises a number of warp threads, each with a respective function in the fabric, with these functions being repeated in each warp thread system. Often the warp threads per warp thread system are drawn through a respective reed opening between two dents of the weaving reed. We should also emphasise that the meaning of the term warp thread system must not be limited in this sense. The warp threads of the same warp thread system can indeed also be spread over two or more reed openings, or the warp threads of several warp thread systems can be present in the same reed opening.
European patent EP 1072705 B1 describes a method in which a series of warp thread systems is provided on a three rapier face-to-face weaving machine comprising binding warp threads, tension warp threads, rib warp threads and pile warp threads. The rib warp threads and the pile warp threads are used as figure warp threads to make a desired pattern visible on the fabrics. At each weaving cycle, three weft threads are inserted at respective weft insertion levels into a shed between the warp threads. The warp threads are thereby positioned relative to the weft insertion levels in consecutive weaving cycles in such a way that two identical fabrics with a rib structure and cut pile are formed above one another. By using two or more differently coloured rib warp threads for each fabric, a desired colour variation can be created into the rib structure.
In order to be able to use rib warp threads with two different colours in each fabric to produce the desired colour variation using this state-of-the-art method, two differently coloured rib warp threads have to be provided in each warp thread system per fabric, hence a total of four rib warp threads per warp thread system.
For each additional colour required to produce the desired colour variation in the two fabrics, two additional figure warp threads with that colour have to be provided in each warp thread system. The increase in the colour variation in such a fabric thus leads to a significantly higher yarn consumption, and naturally has a negative influence on the yarn consumption, the production costs and the weight of the fabrics.